Marijuana Not So Green: Study Finds Growing Pot Indoors Is Energy Intensive

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A room full of marijuana plants is seen inside a house during a raid in Miami-Dade County, Fla.

Wilfredo Lee/AP

A room full of marijuana plants is seen inside a house during a raid in Miami-Dade County, Fla.

Wilfredo Lee/AP

A staff scientist at the Lawrence Berkeley National Laboratory studied the energy use of indoor marijuana growers and found it's an inefficient and energy intensive practice. Evan Mills, who undertook the study independently, reports that:

— "Cannabis production results in energy expenditures of $5 billion each year."

— The electricity use is equivalent to that of two million average U.S. homes.

— It accounts for one percent of national electricity consumption.

To put it in more real-life terms, Mills writes that one joint "represents two pounds of CO2 emissions, an amount equal to running a 100-watt light bulb for 17 hours with average U.S. electricity."

Mills writes that his study doesn't prescribe policy; it just simply states that criminalizing marijuana has made the process of growing it inefficient. Mills also says that this is not "just a California problem." California, which has legalized medical use of marijuana, accounts for 20 percent of "Cannabis-related emissions" in the country.